Abstract: Photovoltaic (PV) module manufacturers are continually pushing for higher efficiency and lower degradation designs. In this push, many manufacturers have opted both for UV transparent encapsulants (to capture more of the solar spectrum) and higher-efficiency n-type PV cells (TOPCon and Heterojunction). The industry is increasingly concerned about the effects of UV light as some of these n-type cells can be very sensitive to “UV induced degradation” (UVID). This concern has prompted Kiwa PVEL to add UVID testing to our product qualification program. We have found that an exposure to 120 kWh/m2 of UV dose, equivalent to approximately 1 year of deployment in Pheonix, AZ, can cause a shocking 16% power degradation on some commercial PV modules.
Despite being a major reliability concern, the underlying mechanism for how UV light damages PV cells is not fully understood. One proposed mechanism is that short-wavelength UV photons (280-360 nm) break Si-H bonds at the SiNx/Si interface, leading to increased surface defect density and reduced efficiency. The PV industry has an urgent need for a detailed mechanistic model of UVID and we will discuss this open research problem.
Bio: Dr. Todd Karin is VP of Technical Operations at Kiwa PVEL. He manages Kiwa PVEL’s product qualification program, which assesses the reliability and bankability of commercial PV modules. He also leads the special projects division, overseeing research projects focused on PV reliability. Dr. Karin holds a Ph.D. in Physics from University of Washington and a B.A. in Physics from UC Berkeley.